U.S. Pat. No. 1,690,557 discloses a wet shaver with a metallic handle. This handle has the shape of a cylindrical rod and has protrusions on its surface. Such protrusions can be created by applying a pattern of parallel lines. The protrusions then have a diamond-shaped base surface and appear as small pyramids. The pattern shown is applied evenly over the entire gripping surface. Such a pattern is primarily suitable for metallic surfaces. When the handle is wet, however, the grip is not optimal. Because the protrusions are all of equal height, the fingers do not have as much hold, particularly as soon as one finger slips off.
DE 10 2004 052 681 A1 discloses a handle, which should be suitable for a multitude of devices. Said handle has so-called acupressure features, which adapt to fit the inside surface of the hand. Thus, the handle provides for a very particular type of hand position. If the device is held in a different position, it is difficult to grip. In fact, with a different grip position, it provides even less secure grip and comfortable grip than a smooth grip. As a result, the advantage of proposing a certain grip position is obtained in exchange for less suitability of the handle for other grip positions.
EP 1 127 529 A1 discloses a vacuum cleaner with a handle section. Said handle section is created by combining a harder plastic material with a softer, more graspable plastic material. The softer plastic material protrudes, in the form of knobs, beyond the hard plastic surface. Thus, the gripping hand obtains a certain amount of security from the knobs. With an electrically operated device however, the grip comfort is at its greatest when the vibrations caused by the electric drive of the device and which are practically unavoidable are transferred to the hand to a limited extent. The disclosed surface comprising hard plastic, which is much larger than the surface of the knobs, does, however, ensures a significant transmission of vibrations.
Therefore, the present invention strives to improve the prior art and to provide an improved surface structure and an improved gripping area for a working device. The surface structure should enable a secure grip and different grip positions while still approaching an optimum grip position. Furthermore, said surface structure should transfer vibrations from the working device in a limited amount and represent an aesthetically pleasing structure.